"spamhog" wrote in message
...
I have a similar practical real problem.

A vertical 120 ft working 75 ohm coax line hung from the top.

The soft foamed dielectric MAY be crushed under the cable's own weight
10 ft from the top end.

If it is I must change the hanging system.

ASSUMPTIONS
- the dielectric is crushed to 1/2 the original thickness over 2
inches length 10 ft from the far end
- I can put a good quality non-reflecting 75 ohm load at the far end.

QUESTION
Can I expect such a defect to generate a detectable reflection at
2GHz?

Yes. The cable impedance will be lowered in the vicinity of the crush.

A good time-domain reflectometer can see the impedance mismatch of
connectors - even you are using types C, N, TNC or BNC. UHF type
connectors, such as the PL-259, are readily seen. Your section of
crushed dielectric should "stick out like a sore thumb" on a TDR trace.
Termination at the far end is not necessary but it will make the
understanding of the TDR waveform easier.

Impedance mismatches, even though they are short in length, become more
important the higher in frequency as you go.

73, Dr. Barry L. Ornitz WA4VZQ